The present invention relates to a contact mechanism used in game devices and the like in which a fixed contact is arranged on a substrate having a predetermined pattern pitch. The contact mechanism is durable, and the output from the contact mechanism is stable.
A conventional contact mechanism is shown in FIGS. 4(a), 4(b), 5(a), and 5(b). FIG. 4(a) shows a fixed contact 1 of a contact mechanism 14. The fixed contact 1 is formed from an approximately E-shaped terminal 2 equipped with a plurality of parallel contacts 2a and a contact connecting portion 2b and an approximately reverse E-shaped terminal 3 equipped with a plurality of parallel contacts 3a and a contact connecting portion 3b. Terminals 2, 3 are arranged on a substrate 4 so that each of contacts 2a are formed adjacent to and alternate with each of contacts 3a. The alternating contacts 2a, 3a have a predetermined pattern pitch.
Terminal 2 is formed in an approximate xe2x80x9cExe2x80x9d shape with a copper foil pattern 5 on the substrate 4. Carbon 6 is applied to cover the copper foil pattern 5 in the approximately E-shaped pattern. Terminal 3 is formed in an approximate reversed xe2x80x9cExe2x80x9d shape with a copper foil pattern 7 on the substrate 4. Carbon 8 is applied to cover the copper foil pattern 7 in the approximately reversed E-shaped pattern.
Contacts 2a, 3a are disposed in an alternating manner and are arranged with a pattern pitch of approximately 0.8 mm. The width of each of contacts 2a, 3a is approximately 0.8 mm, and the distance separating adjacent contacts 2a, 3a is approximately 0.8 mm.
A movable contact 10 is formed from a pressure-sensitive element 9 which is adhered to the fixed contact 1 using an adhesive 11. The adhesive 11 is applied in a predetermined pattern as shown in FIG. 4(b).
The pattern of the adhesive 11 results in the formation of spaces 12 where the adhesive 11 is not applied at predetermined positions between the movable contact 10 and the alternating contacts 2a, 3a of the fixed contact 1. The spaces 12 separate the alternating contacts 2a, 3a of the fixed contact 1 from the movable contact 10 to allow contact. Thus, the adhesive 11 serves as a spacer.
A rubber piece 13 is disposed above the movable contact 10 so that it can contact and move away from the movable contact 10. The rubber piece 13, the movable contact 10, and the fixed contact 1 form the contact mechanism 14.
The bottom end of the rubber piece 13 of the contact mechanism 14 pushes down on the pressure-sensitive element 9 of the movable contact 10 above the space 12 when the rubber piece 13 is pressed downward. The pressure-sensitive element 9 contacts the fixed contact 1 and generates an output. The downward force on the pressure-sensitive element 9 and the output level from the contact mechanism 14 increase as the rubber piece 13 is pushed down.
FIG. 5(a) is a graph illustrating the relationship between the level of the output and the downward force on the rubber piece 13 after 2 million operations of the contact mechanism 14. The graph shows measurements from a sampling of 18 contact mechanisms. The results indicate that the relationship between the output level and the downward force varies after 2 million applications. The output level is unstable, and the error in the output level increases slightly with each sample.
FIG. 5(b) is a graph illustrating the relationship between the level of the output and the downward force on the rubber piece 13 after 10 million operations of the contact mechanism 14. The relationship between the output level and the downward force is considerably less stable than the relationship shown in FIG. 5(a). The output is extremely unstable and the output error is higher for each sample as the number of applications increases.
The results in FIGS. 5(a) and 5(b) indicate that the output from the contact mechanism 14 will vary even when the usage count is low, and the output level varies depending on the individual sample. Furthermore, the stability of the output level is severely degraded, and the contact mechanism shows inferior durability as the usage count increases. The variation of the overall output level and between the output levels of each sample are high.
A possible cause for error is the wide spacing of the pattern pitch of the contacts 2a, 3a of the fixed contact 1. The contact position between the movable contact 10 and the contacts 2a, 3a of the fixed contact 1 is misaligned, and this misalignment leads to instability and errors in the output levels. Another possible cause for error is the repeated use of the contact mechanism 14. The substrate 4 under repeated use becomes damaged near the ends of the copper foil patterns 5, 7 since the ends of the copper foil patterns 5, 7 are pressed against the carbons 6, 8. The repeated use of the contact mechanism 14 increases the error in the output levels.
The present invention provides a durable contact mechanism having stable output levels. The contact mechanism comprises a fixed contact and a movable contact. The fixed contact is formed by arranging two terminals having a plurality of parallel contacts so that the contacts are disposed in an alternating manner and at a predetermined pattern pitch. The movable contact is disposed above the contacts of the fixed contact to be able to connect with the contacts of the fixed contact. The pattern pitch of the contacts is set within a range of 0.4 mm-0.8 mm. The contacts of the fixed contact can be made of carbon formed on the substrate. The contacts of the fixed contact can be formed from carbon covering a copper foil pattern formed on the substrate. Furthermore, the movable contact can be a pressure-sensitive element.
The objects, features, and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings in which like reference numerals designate the same elements.